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Presentation about 'Textile chemical Dictionary'
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TEXTILE CHEMICAL DICTIONAREY
Prepared By : Prepared By : Mazadul Hasan sheshir ID: 2010000400008 13thBatch (session 2009-2013) Department : Wet Processing Technology Email: mazadulhasan@yahoo.com Blog : www. Textilelab.blogspot.com (visit) Southeast University Department Of Textile Engineering I/A 251,252 Tejgaon Dhaka Bangladesh
MX dye - a family of “cold” reactive dyes, first developed by Imperial Chemical Industries of Britain, and designated “Procion MX”; chemically MX dyes belong to the dichlorotriazene family A number of companies now manufacture MX dyes. They are by far the most popular dyes for textile artists working with cellulose fibres. They can also be used for wool and nylon in processes where they behave as acid dyes. There are around a dozen “pure” MX dyes in common use, and all can be used quite successful in mixtures with each other. There are magenta, yellow and cyan shades that are excellent “subtractive primary” colors. MX dyes are less popular with industrial dyers than some other reactive dyes, partly because their very high reactivity makes the dye process harder to control, partly because they are fairly expensive, and partly because goods require extensive washing after dyeing to remove hydrolyzed and unfixed dye. Care should be taken to avoid breathing MX dye dust, since it is known to cause respiratory allergies. The use of “Procion” alone to denote MX dyes is incorrect since there are other Procion dye families.
Nylon - A polyamide used for fibres and solid plastic 1. There are several different types of nylon, each having different properties. 2. Two common ones, based on molecular structure are nylon 6 and nylon 6,6 (nylon six six). Nylon is the oldest synthetic polymer used for textiles. 3. It is usually dyed with acid dyes, but can be dyed with disperse dyes, particularly if barré is a problem. 4. For acid dyeing, nylon can be formulated specifically to take up only a little dye, “normal” amounts of dye, or large amounts of dye.
Optical Brightener - A fluorescent dye used to make white textiles appear brighter; often called just “optical” in dye industry; also called fluorescent brighteners or fluorescent brightening agents (FBA) 1. Optical brighteners are colorless dyes that work by emitting visible light, typically in bluish hue, when exposed to invisible ultraviolet light. 2. This bluish tint helps mask the residual yellowish cast of bleached cellulosic fibres and wool, making the fabric appear a more neutral white. 3. Most fully-bleached commercial white fabrics have been treated with these brighteners. 4. Fabrics and garments that are truly prepared for dyeing should not contain brighteners. 5. Optical brighteners can interfere with some dyes by competing for the “dye sites” on the fibres.
It is almost impossible to remove brighteners once they are applied. Most commercial laundry detergents contain optical brighteners, which is primarily the reason that they are not the best choice for scouring fabric prior to dyeing. When detergent containing optical brighteners is used to wash brightener-free fabric that has been dyed to pale shades, noticeable shade change may occur.
OWF (or o.w.f.) - On weight of fibre, usually expressed as percentage; omf is on mass of fibre - preferred modern Usage Often this is synonymous with owg but distinction may be appropriate when considering a particular fibre in a blend. OWB (or o.w.b.) - On weight of bath; usually expressed as percentage; omb is on mass of bath - preferred modern Usage The amount of some constituent of a dyebath or other process bath based on the weight of the bath. For example, something specified as 6% owb would require 0.06 pounds of that item per pound of bath. Since the bath is invariably mostly water, which weighs 1 kilogram per litre, calculations in the metric system are much easier. OWG (or o.w.g) - on weight of goods; usually specified as percentage; omg is on mass of goods - preferred modern Usage The amount of dye or auxiliary chemicals used is often based on ratio to the weight of the goods to be dyed. For example, if a formula calls for 3% dye owg, and 400 grams of fabric are to be dyed, the required amount of dye would be 3% of 400 grams, or 12 grams. Owf may be more accurate when blended fibres are considered.
Oxidizing Agent - A chemist’s term for any chemical that causes loss of electrons from another chemical with which It reacts; the oxidizing agent is itself reduced (see reducing agent) in the process Oxygen is the oxidizing agent whence the name comes. Chlorine is another strong oxidizing agent. As an example, when sodium reacts with chlorine, sodium chloride (common salt) is formed. Sodium loses an electron in the process (going from Na to Na ), and chlorine gains an electron (going from Clto Cl ). Strong oxidizing agents+-must be handled with care, since contact with substances that burn may cause fire.
Padding - A dyeing method with very low liquor to goods ratio, where typically only enough strong dye solution is 1. Used to saturate the fabric Padding can have the advantage of high dye yield. 2. Padded goods are usually “batched” - wrapped in plastic and left for some period of time for the dye to attach to the fibre, or steamed to fix the dye quickly. 3. Padding methods are sometimes used for other textile processes such as bleaching.
Pantone® - a company and its trademark The Pantone company produces a wide range of color guides useful in almost any industry dealing with color. The colors in the guide are widely accepted as standards. Colors are sometime seen described as a Pantone number: Pantone applies a unique number to each color.
Pigment - A colored substance that is insoluble in water, usually in the form of a fine powder 1. Pigments are used to color many types of paint, including some textile paints, and almost all “inks” used for screen printing (“silkscreen” printing) . 2. Pigments need some sort of binder to hold them onto fabric. Azoic dyes and vat dyes actually form pigment inside fibres. 3. These pigments are physically trapped inside the fibre, so no binder is necessary. 4. Inorganic pigments are often oxides of metals, such as iron oxide or titanium dioxide. 5. Many organic pigments are chemically similar to parts of dye molecules, but lack the necessary features to make them soluble and to bond, unaided, to the fibre.
Pigment Dyeing - Coloring fabric with pigments mixed with a binder; this term is considered to be improper, since 1. ‘dyeing’ is generally restricted to application of colorants that are soluble, and pigments are insoluble Some pigment application processes are much like dipping the fabric in a dilute paint. 2. Newer processes involve pretreating the fabric with substantivity-producing agents that actually make the process more like true dyeing, where the pigment preferentially leaves the bath and attaches to the treated fabric. 3. So-called pigment dyed fabrics often have, by design, poor washfastness, to produce an aged appearance. 4. Commercially, pigment dyeing is generally used more for finished garments than for fabrics.
Plastisol - With reference to textile arts, a type of screen printing (‘silkscreen’) ink which consists of a colored 1. pigment, fine particles of polyvinyl chloride, and a plasticizer Plastisol ink does not dry. 2. It must be heated to the point where the PVC particles melt and mix with the plasticizer and pigment to form a flexible colored plastic film. 3. Plastisol ink stays on fabric simply because is surrounds and encapsulates the fibres mechanically. 4. This is by far the most popular type of ink for commercial screen printing of t-shirts and the like.
Polyamide - A synthetic polymer family used for fibres and solid plastics; protein fibres are also technically 1. polyamides, but the term is almost always used only for synthetic materials Nylon is a polyamide, and the oldest of the commercial synthetic polymers. 2. Polyamide can be dyed with acid dyes or disperse dyes. 3. Some MX dyes will also work well for nylon if applied as if they were acid dyes (at acid pH and high temperature).
Polyester - A somewhat generic term used for a variety of synthetic polymers used both for solid plastics and for fibres; polyethylene Terephthalate is probably the most common Polyester is are harder to dye than many other fibre polymers. It is dyed almost exclusively with disperse dyes. 1. Because of its high glass transition temperature, dyeing is usually done at high temperature (around 130°C) in a pressure vessel. Carriers can be used for dyeing at the boil. 2. Washfastness of polyester is very high because it is almost impenetrable to water even at the boil. 3. Some polyester is formulated to allow dyeing with basic dyes. 4. Polyester containers (often labeled PET or PETE), very popular for beverages, can be used for dye solutions, at least for short term storage. 5. Polyester is attacked by strong alkalis. A few stitches of brightly-colored polyester thread can be handy for ‘labeling’ items being dyed in almost any process other than disperse dyeing, because they will retain their original color.
Polyethylene - a synthetic “olefin” polymer (plastic) 1. Polyethylene, particularly high-density polyethylene (HDPE), is a good choice for containers for many dyeing processes. 2. It has good chemical resistance, but generally should not be subjected to boiling water (see polypropylene for an alternative). 3. A great deal of the commercial packaging for household chemicals and food products is made from polyethylene. 4. Some fabric sizing compounds and softening compounds are polyethylene derivatives.
Polypropylene- a synthetic “olefin” polymer (plastic) 1. Polypropylene containers are a good choice for many dyeing processes. 2. Polypropylene has excellent resistance to most chemicals used in dyeing, with the possible exception of some disperse dye carriers. 3. It can be used at the boiling point of water, though it can’t be used on a stove top. 4. A great many household plastic containers are made from this polymer. 5. Polypropylene is also used for fibres, mostly for carpets, but finds some use in garments. It cannot conventionally dyed so it is colored by “dope dyeing” (pigments are added to the raw material).
Polystyrene- A synthetic polymer (plastic) 1. Polystyrene is extensively used for disposable food service and packaging items. 2. Solid polystyrene is used for disposable cutlery, glasses and portion cups. 3. Foamed polystyrene is used for plates, packaging trays, coffee cups and the like. 4. Polystyrene has poor resistance to many organic chemicals. 5. Do not use it for storage of dry dyes. 6. Polystyrene items are very convenient for short-term handling dye powders when weighing or mixing dyes.
Potassium Dichromate - Also called potassium bichromate; K2 Cr2 O7 Potassium dichromate is the most commonly used chromium (‘chrome’) mordant in wool dyeing, both with synthetic and natural dyes. In terms of health risks of repeated exposure, 1. It is one of the most hazardous chemicals used by textile art dyers 2. It is corrosive to tissues and can cause ulceration. 3. It is known to be a human carcinogen. 4. It poses serious disposal problems . 5. Do not use this chemical unless you have consulted and understood a material safety data sheet(msds) 6. for it and have the necessary safety equipment
Potassium Permanganate - KMnO4 1. Potassium permanganate is a powerful oxidizing agent which has been used in garment washing indigo-dyed denim to produce a worn, faded appearance. 2. It has also found some use in discharge printing of indigo. 3. It is no longer favored by industry because of environmental concerns. 4. It is quite hazardous, and can be caustic to skin. Caution !!!! Care must be used when mixing it with organic materials because it can cause spontaneous combustion. Consult an MSDS if you contemplate using it.
PRE-METALLIZED DYE - A dye that is a complex of dye molecules with a metal atom; metal complex dye The term “pre-metallized” is used primarily to refer to classes of acid dyes, although sometimes considered as apart from acid dyes. The metal is part of the dye structure as it comes from the manufacturer. There are 1:1 metallized dyes, having one dye molecule per metal atom, and 2:1 types, with two dye molecules per metal atom (use is inconsistent here 2:1 and 1:2 mean the same thing). The metal in the complex helps the dye attach to the fibre, typically wool or polyamide. These dyes have excellent washfastness, but leveling may be difficult. There is a wide range of “pure” colors (as opposed to mixtures) available, though the brightness is the lowest of the acid dye subgroups. Application temperature is typically at or near the boil. 1:1 types are usually applied at very low pH, often with formic or sulfuric acid in quite large quantities, while 2:1, sometimes called “neutral dyeing”, are often applied using acid donor chemicals, so the bath is nearly neutral at the start an becomes more acid with continued boiling.
Prepared for dyeing - A fabric or garment that is specially made to be dyed; sometimes “preferred for dyeing”; usually abbreviated pfd or p.f.d. PFD fabrics have been desized, scoured, and fully bleached, but have been processed without optical brighteners or softeners which can interfere with dye uptake. Often called ‘prepared for garment dyeing’ or PFGD, such fabrics are usually only carried by specialty suppliers. Most fabric is prepared for dyeing at the same facility that does dyeing. Any fabric can be prepared for dyeing and sold as such, but types other than cotton are extremely rare, and often available only by special order of large quantities. PFD cotton garments are made with PFD fabrics and sewn with cotton thread, so that the thread will dye similarly to the fabric. Sometimes they are made oversize to allow for shrinkage in dyeing processes. A few large manufactures of t-shirts offer PFD shirts. Other PFD garments are quite rare, though Dharma Trading in California has quite a good range. It may be advisable to wash PFD products before dyeing, mostly as a hedge against contaminants picked up in handling or to remove thread lubrication oils that might have been used in garment construction.
Reactive dye - A dye which attaches to the fibre by forming a covalent bond; also called fibre reactive dye 1. Reactive dyes are known for their bright colors and very good to excellent lightfastness and washfastness, though poor resistance to chlorine bleach. 2. There are several broad classes of reactive dyes. Most are intended for cellulose fibres, but some are intended specifically for wool. 3. The most popular reactive dye family for textile artists is the Procion® MX family. 4. Other reactive dye families reasonably available to art dyers include Procion® H, Procion® H-E, Remazol®, and Cibacron® F (equivalents to the MX, H, H-E and some of the Remazol® lines are available from many dye manufacturers; note that Procion®, Remazol® and Cibacron® are trade names of specific companies). 5. Reactive dyes may be more expensive than other dye families suitable for the same fibres, especially when very dark or dull colors are considered.
1. They are the newest class of textile dyes, first introduced commercially, for cellulosic fibres, in 1956 , one hundred years after the development of the first synthetic dye. 2. Within a family, the range of colors available as “pure” dyes (as opposed to mixtures) is typically quite small – a dozen or fewer. 3. Against this, reactive dyes of the same family can generally be mixed to produce a very wide range of colors, while retaining good application characteristics and brightness. 4. The reactivity among families varies widely, so some are easily applied at room temperature, some at boiling temperature and others at intermediate temperature. 5. All types are suitable for exhaust dyeing, and many types are suitable for pad-batch (see padding) dyeing and for printing. 6. Apart from cost, the biggest commercial drawbacks to reactive dyes are that they require large amounts of electrolyte (salt) in most processes, and extensive rinsing and hot washing after dyeing to remove
Reducing Agent - A chemist’s term for any chemical that causes gain of electrons by another chemical with which it 1. reacts; the reducing agent is itself oxidized (see oxidizing agent) in the process Many reducing agents are used in dyeing processes. 2. They include thiourea dioxide, sodium bisulfite, sodium formaldehyde sulfoxylate, sodium hydrosulfite and others. 3. They are often used in discharge and stripping processes, and are used for converting insoluble vat or sulfur dyes to the soluble form. 4. Solid-chemical reducing agents are often flammable.
Reduction Clearing - Removal of disperse dye on the surface of fabric by use of a reducing agent 1. Fine particles of disperse dye often remain on the surface of dyed fabric. 2. These particles can cause wash fastness problems, yet are hard to fully remove by washing alone. For polyester, a mixture of about 2 grams per litre each of sodium hydrosulfite and sodium carbonate is used at about 70 degrees Celsius for about 20 minutes. Dye inside the fibre is not effected by this treatment.
RESERVING AGENT - Also called restraining agents; a dye bath auxiliary that is typically used to prevent one fibre in a 1. blend from taking up dye intended for the other fibre, or to equalize the uptake When blends are dyed, one fibre may be truly dyed while the other is stained (colored, but with very poor fastness). 2. Reserving agents can be used to significantly reduced the undesired staining. 3. In blends such as wool+nylon, reserving agents can act to reduce the dye uptake by the nylon, so that the nylon and wool ultimately a colored similarly.
Resist - In dyeing (and some other processes), something applied to fabric to prevent dye from coloring it 1. Resists such as waxes used in batik simply prevent dye from gaining access to the fibre. 2. Tie-dyeing and shibori employ what amount to mechanical resist methods to limit dye access. 3. Chemical resists allow the dye to gain physical access to the fibre, but prevent fixation of the dye to the fibre. 4. These include sulfites such as sodium bisulfite, as a resist for vinyl sulfone dyes, citric acid as a resist for many reactive dyes for cellulosic fibres, and sulfamic acid as a resist for acid dyes on wool.
Resist Salt - An oxidizing agent added to dye baths or print pastes to prevent reduction damage to dyes 1. Under some conditions, especially where air is excluded, such as in steam fixation of dye, some of the dye may be decomposed by reduction (often the fibre itself acting as the reducing agent). 2. Resist salts, such as sodium mnitrobenzene sulfonate, generally used in alkaline conditions, or sodium chlorate, generally used in acid conditions, may be added to prevent this. 3. Resist salts are also sometimes applied to fabric before printing with discharge pastes to protect the ground color dye and/or improve the sharpness of edges of the discharge. 4. This term is a bit misleading: don’t confuse resist salts with chemicals used to keep dye from fixing to the fibre.
Retarder - the fibre; also called leveling agents A chemical added to a dye bath to reduce the rate at which dye attaches to 1. A retarder may be required to prevent a dye from attaching to fibres so quickly that it would be very difficult to achieve level dyeing. 2. Retarders are often used with acid dyes. 3. They may work by quickly attaching to the fibre thereby temporarily keeping the dye from attaching, or by quickly attaching to the dye, temporarily keeping the fibre from attaching to the dye. 4. Simple chemicals such as sodium sulfate may act as retarders for some dyes in some conditions. 5. There are many retarders on the market that are proprietary mixtures of chemicals, often formulated to be companions for specific dye families. 6. Reserving agents can be thought of as a special class of retarder. 7. The availability to art dyers of retarders is limited.
Remazol® - a family of vinyl sulfone reactive dyes; tradename of Dystar of Germany roman numerals in chemical names Many ions can assume different electrical charges in different compounds. For example, iron can have a charge of +2 or +3. For example, in old use, iron chloride (FeCl ) where the iron has a charge of +2, would be called 2 “ferrous chloride”, while FeCl , where the iron has a charge of +3, would be called “ferric chloride”. In modern use, 3 FeCl would be called “iron (II) chloride” (read as iron two chloride) and FeCl would be called “iron (III) 2 3 chloride” (read as iron three chloride). The roman numerals directly indicate the charge. In dyeing, this is most likely to be found in aluminum, chromium, copper, iron, tin and zinc compounds.
SCOUR - essentially, thoroughly washing fibres or fabric to remove contaminants Yarns and fabrics may be dirty, contain natural waxes or oils, or have been treated with size or lubricants used in spinning, weaving or knitting. These can all interfere with dyeing, often leading to non-level results. Scouring is a large topic, and the process used depends on the fibre type and its condition. “True” scouring of greige cellulosic fabrics is typically done, after desizing, at the boil or at higher temperature in pressure vessels, with as much as 10 grams sodium hydroxide per litre of water, plus surfactants, and the process may last for several hours. Commercial scouring of wool may use solvents, similar to dry cleaning, as part of the process. White fabrics sold at retail have normally be scoured at the mill; “natural” fabrics usually have not (some “natural” fabrics have been scoured but not bleached). Art dyeing literature often refers to what amounts to laundering as scouring. This is inadequate for greige fabrics, but often quite acceptable for “white goods”. A long machine wash with the hottest water possible, about a gram of soda ash per litre of water (about a teaspoon per gallon) and some (preferably optical brightener free) detergent, followed by two rinses is usually acceptable. Sodium hexametaphosphate may be helpful if the water is hard. Woven white cottons often contain starch that will not be removed by such a limited process.
Sequestering Agent (or sequestrant) - A chemical compound that tends to bind some ‘species’ such as metal ions and keep them from being available to participate in other chemicalreactions; also called chelating agents Chemicals such as sodium hexametaphosphate, citric acid or EDTA , the choice depending on considerations such as pH and dye type, are used to sequester hardness ions such as calcium and magnesium and metal ions such as iron and copper. Caution !!! Care must be taken with pre-metallized dyes, since some powerful sequestering agents can actually remove the metal from the dye complex.
Shelf Life - The period of time some product can be stored “on the shelf” before it degrades to some point of reduced 1. Effectiveness Some chemicals, including dyes, have limited shelf life. 2. They degrade over time, eventually becoming completely useless for their intended purpose. 3. Useful shelf life may range from hours to hundreds of years. For example, an enzyme used for desizing might be specified as losing about 10% of its strength after storage at 20°C for 4. six months - it is still very useful, just slightly weaker. 5. Shelf life is generally maximized by storage at low temperature (sometimes even freezing, but this can damage some products). 6. Chemicals should also usually be protected from long exposure to bright light, and dry chemicals should be protected from humidity by storage in tightly closed moisture- proof containers.
SINGEING - an industrial defibrillation process where rapidly-moving fabric passes over a flame or a very hot plate in order to burn away fibres poking up from the surface. Also see gassing. SIZE (or sizing) - in textiles, a material applied to yarns or fabrics to make them stiffer or temporarily bind fibres together Sizing is used extensively, especially for cellulose fibres, to make them easier to process or protect them from damage during high-speed weaving or the like. A wide variety of compounds, including starches and other plant derivatives, and synthetic organic compounds, such as polyvinyl alcohol, are used for sizing. Sizing materials can interfere with dyeing, so it is important that they are removed by desizing, usually prior to scouring but sometimes as part of the scouring process.
Soaping (or soaping off) - with respect to dyeing, the process of washing dyed fabric with very hot (often boiling) 1. water with surfactants, rarely actually soap, to remove dye that is not fixed to the fibre. 2. Soaping off is important particularly with some reactive dyes, since a good deal of hydrolyzed dye is loosely bonded to the fabric, and must be removed to avoid staining of other garments or fabric in laundering. 3. Soaping is also important in vat dyeing, where there are actual changes, including in hue, in the dye in the fibre. 4. Though surfactants are often used, they may actually contribute almost nothing to the effectiveness of the process.
SODIUM BICARBONATE - NaHCO ; more properly called sodium hydrogen carbonate; also called sodium acid carbonate, and most commonly, baking soda Sodium bicarbonate is used as a weak base (alkali) in some dyeing processes, often with reactive dye that is padded onto fabric, then batched for many hours. It has limited stability in solution, decomposing to sodium carbonate, carbon dioxide and water, especially at high temperature, so solutions generally should be made shortly before use. Sometimes this decomposition is used deliberately, usually with highly reactive dyes such as MX. A print paste made with sodium bicarbonate will have a pH around 8, and at this pH the dye will not hydrolyze rapidly and hence become useless. When the printed fabric is steamed, the sodium bicarbonate will decompose and the Ph will rise to around 11, facilitating reaction of the dye with the fibre.
sodium bisulfate - NaHSO ; also called sodium hydrogen sulfate or sodium acid sulfate Sodium bisulfate hydrolyzes in water solution, and acts much like sulfuric acid. It can sometimes be used as substitute for sulfuric acid, and because it is a dry chemical, it can be safer to handle, though care is still necessary. Sodium bisulfate is often the basis for etchant pastes for devoré of cotton. “pH Down” for spas and swimming pools is usually sodium bisulfate. Do not confuse this with sodium bisulfite.
SODIUM BISULFITE – NaHSO3 ; a mild reducing agent, most used in dyeing as an antichlor; often actually sodium metabisulfite (Na2 S 205 ), which behaves the same way As an antichlor, sodium (meta)bisulfite reacts with sodium hypochlorite and hypochlorous acid, to almost immediately stop bleaching action. The product of the reaction is two acids which need to be thoroughly rinsed from the fabric. Typical use is about a gram (approximately 1/4 tsp) per litre of room-temperature water. Solutions should be prepared shortly before use (preferably within an hour) and with gentle stirring, since oxygen dissolved in the solution will destroy its effectiveness. Discard used solutions. Do not confuse this chemical with sodium bisulfate. CAUTION !!! Some people develop very serious sensitivity to sulfite compounds.
sodium carbonate - soda ash; Na2 CO3 ; a weak base Sodium carbonate is an extensively-used alkali in textile preparation and dyeing. It is typically used to adjust the pH of solutions to about 11. It is also used in scouring cellulose fibres. The most common industrial form is theanhydrous type. Sodium carbonate monohydrate (Na CO •H 0) is the most common form sold for photographic use. Washing soda, if “pure”, is usually sodium carbonate decahydrate (Na CO •10H 0). Soda ash is hygroscopic, so it should be stored in a tightly-closed moisture-proof container. If so protected, it will keep indefinitely. See also pH Up and hydration state.
sodium formaldehyde sulfoxylate - a reducing agent used in discharge techniques and for stripping dye; Trade names are : Formosul and Rongalit C; designated in Colour Index as Reducing Agent 2 This chemical is useful for discharge on cellulose and silk, but not usually on wool. It requires alkaline conditions that may damage wool (alkaline conditions can also reduce the sheen of silk). It does not contain free formaldehyde. Also see zinc formaldehyde sulfoxylate.
SODIUM HEXAMETAPHOSPHATE - Na P O , where x = 6 to 21; a sequestrant used to treat hard water; SHMP, (x+2) x (3x+1) often referred to in art dyeing literature as “metaphos” Sodium hexametaphosphate softens water by sequestering calcium and magnesium, effectively making them unavailable to participate in other reactions. Typical use would be about 0.5 grams per litre of water. Calgon T is one trade name for sodium hexametaphosphate, though retail Calgon products contain other chemicals, and are not the preferred products for dyeing applications.
SODIUM HYDROXIDE - NaOH; a strong base; commonly sold as beads or flakes, or as a 50% solution; also called caustic soda or lye, often just called “caustic” in dyeing Sodium hydroxide is used in some dyeing processes requiring very high pH. A solution of 4 grams per litre will have a pH of 13. It is common in vat dyeing, some reactive dye methods, and is used in mercerizing cotton. It is commonly used for industrial scouring of cotton. Sodium hydroxide must be handled with great care, since it will cause severe skin burns. It should be dissolved by SLOWLY adding it to stirred VERY COLD water, since a great deal of heat is liberated as it dissolves. Never use aluminum vessels or tools with NaOH: they will be corroded, and explosive hydrogen will be generated. Sodium hydroxide is deliquescent - extremely hygroscopic.
SODIUM HYDROSULFITE - Na 2S2 04 ; a reducing agent used in discharge techniques, dye stripping, and in vat dyeing; more properly called sodium dithionite; dyehouse term is “hydro” or “hydros” For stripping, it is usually used in an alkaline solution at a temperature near the boiling point of water. This is the active ingredient in some of the “whiteners” or “dye removers” sold in small packages like the “household” dyes in the grocery store. It produces a rather strong sulfurous smell. Sodium hydrosulfite is a flammable powder, and must be handled with care. Do not confuse this with sodium hydrosulfide, which is used with sulfur dyes.
sodium m-nitrobenzene sulfonate - often referred to by BASF’s tradename Ludigol® This chemical is a mild oxidizing agent that is sometimes used to protect dyes from degradation caused by reducing conditions that exist at high pH and high temperature, especially where air is excluded from the dyeing vessel. Such conditions are quite common in processes for some of the low-reactivity dyes, but very rare in processes for MX dyes, except in steam fixing. Recommended amounts for protecting dyes from reduction range from 1 to 10 grams per litre of dyebath. When used in printing it is sometimes called a resist salt. It is also used as an oxidizing agent for some vat dyes.
SODIUM PERBORATE – NaBO3 This is the bleaching compound that is most commonly found in laundry detergents that contain “color safe” bleach. Such detergents often contain special activators that make the perborate work more effectively at moderate temperatures.
SODIUM PERCARBONATE - a dry chemical made by reacting sodium carbonate with hydrogen peroxide Sodium percarbonate can be used as an alternative to hydrogen peroxide for oxidizing bleaching. It is considerably more expensive, but is safer to handle (relative to industrial- strength hydrogen peroxide). Oxi Clean® is a retail cleaning compound believed to be primarily sodium percarbonate.
sodium sulfate - Glauber’s salt; Na2 SO4 Sodium sulfate is used as an alternative to common salt (sodium chloride) in some dyeing processes, such as those involving MX turquoise where it is a simple electrolyte. When used with some acid dyes for wool, it may act as either an electrolyte to enhance exhaustion, or as a retarder to aid leveling, depending on conditions such as pH. It is also used as a diluent for many dyes. Sodium sulfate is often sold in anhydrous form. It will absorb water from the air, so it should be stored in tightly closed containers. In the dye industry, some use “sodium sulfate” only to refer to the anhydrous form, and “Glauber’s salt” to refer to the decahydrate form (Na 2SO4 •10H2 0).
